1. Field of the Invention
This invention relates an ultrasonic wave therapeutic device, more particularly a device for therapeutically treating tumors, calculi and so on, in which an ultrasonic wave generated outside the body is converged on an object having the tumors, calculi etc. inside the body.
2. Related Art Statement
As described on page 173 to 174 (Convergency of ultrasonic Waves) of the Handbook of Ultrasonic Wave Technology, on rotating parabolic surface reflector (called paraboloid reflector hereafter) and a reflector of straight cone of 90 degrees, are coupled; an ultrasonic wave incident on the straight cone reflector is reflected in all of the horizontal directions, as a cylindrical wave; then, the ultrasonic wave is reflected, again, by using a paraboloidal reflector so as to converge it on the focus. Such a device is known as a parabolic concentrator, and was disclosed by A Barome in 1952.
Japanese patent laid open No. 1985-214211 discloses an ultrasonic converging device, in which a conical horn of acute, top angle is arranged on the same axis as that of a horn having a paraboloidal surface so that the device is made small. And, Japanese patent laid open No. 1986-51511 discloses an ultrasonic wave converging device with a horn, in which an aperture of an end of ultrasonic wave transmitting and receiving elements is formed smaller than that of their front surfaces. Moreover, Japanese patent laid open No. 1986-170446 shows, as a shock wave generator, a device having a conical reflector and a reflector of inner paraboloidal reflecting surface, which is arranged on the common focus area, and any one of the above described reflectors can be replaced. Japanese patent laid open No. 1986-154658 proposes a shock wave tube having a conical reflector and a casing of inner paraboloidal reflecting surface, both of which move along the central axis of a shock wave generating means so as to change the focus of ultrasonic waves.
When the above described ultrasonic wave converging device is used for medical treatment, a converged situation of ultrasonic waves should be changed adequately depending on the condition of the object to be treated, because sizes and shapes of a tumor and a calculus are different for each individual patient.
However, in the above described prior art, it is necessary to move the ultrasonic wave generator itself in order to change the position of ultrasonic waves to be converged; thus, the ultrasonic wave cannot be focused on the object to be treated, a wide area cannot be treated at one time, and shock wave strength and its distribution cannot be changed at the focus of converged ultrasonic waves. Therefore a desired focusing condition of the ultrasonic wave cannot be obtained in accordance with a situation of objects to be treated.